Mathematically, which was the shortest century?

Answer 1

That would be the 16th century, due to the Gregorian reform. In the year 1582, Thursday, October 4 was immediately followed by Friday, October 15, resulting in a century that was 10 days shorter than any other. However, some countries adopted the Gregorian calendar later; several countries skipped 11 days at various points in the 17th and 18th centuries (because the longer a country waited to adopt the calendar, the greater the amount of correction required). Russia and Greece were the last countries to adopt it, finally doing so during the 20th century and thus having a century that was short by 13 days.

Please note that every century always starts in a year ending in 01. The 16th century started in 1501. The 21st century started in 2001. So this suggestion that the 1st century was short by a year because it started in year 1 instead of year 0 is inaccurate.

Answer 2

The first century began in year 1 and ended at the end of year 100 (total duration = 100 years);
The next one was 101-200; then 201-300 (inclusive);
until 1901-2000,
The present century began on Jan. 1 2001, even though English speaking countries continued the erroneous trend that began in Germany in 1800 of starting a century on the wrong year.

The key is in the date at which the year began.

The first 6 centuries don't count (1 to 500) because they were "created" after the fact (the calculation to determine year 1 was done in the middle of the 6th century -- Dionysius Exiguus in what we now call AD 532). The celebration of the birth of Christ (Christmas) had already been placed on December 25 to replace a Roman "pagan" celebration, and the christian year 1 began on December 25 of the year that we now call 1 BC.

For a while, it was common to begin the year at Christmas (December 24 of year X was followed by December 25 of year X+1).

Then the year began at Easter, with the Saturday before Easter Sunday being in year Y and Easter Sunday being in year Y+1.

So, somewhere, there is a century that began on December 25 of what we, today, would call year xx00, and finished on the Saturday before Easter, of the year we would call yy01 (where yy = xx+1). Total: 100 years + 3 months or so (depending on the date of Easter on the year the next century began).

The shortest century is the one that contains the year when the New Year date was moved from April to January 1st. Total 99 years and 9 months. After the change of New Year to January 1st, it was customary to call "April Fools" those who still celebrated the New Year on April 1. In France (and in many Roman Catholic countries) that would be the 16th century, as Charles IX decreed that France woud celebrate the arrival of the New Year 1565 on January 1 (making 1564 the shortest year, I guess).

The passage from Julian to Gregorian only removed 10 to 12 days (depending on the year at which a particular country made the change). In Roman Catholic Europe, this change also took place during the 16th century (1582), so that the century was even shorter: 99 years, 8 months and 20 days (give or take a few).

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A long time ago (more than 10 years ago), some historians hinted that maybe the ninth century (801-900 incl.) was cut short because some years were skipped near the end -- just after 888. However, I looked for hints of this elsewhere (a change this big would have been noted somewhere!) and found nothing.

The reason for the missing years, if I remember well, was to avoid the expected end of the world when the age of the Earth reached 6000 years since its biblical creation. However, with what we now know about the years "since creation", if such a thing occurred, it would have occurred in the last years of the eighth century (790's) not in the ninth. The same fear of the y6k end of the world is what did away with the calendar based on years since the biblical creation and made the AD calendar more popular.

But that is a different story. Indirectly, it involves the crowing of Charlemagne by the pope...

Answer 3

The first.

It started at year 1... not year 0.

Answer 4

I suppose the first one; it started at 1AD, as opposed to all of the others:

100-200AD
200-300AD
etc.